High aspect ratio etching of 2D-photonic crystals in InP/InGaAsP/InP heterostructures

Summary form only given. The talk will focus on the fabrication of 2D photonic crystals (PCs) in InP/InGaAsP/InP heterostructures by dry etching techniques with specific attention to Ar/Cl₂ based chemically assisted ion beam etching (CAIBE) and summarizes the ongoing research activities at the Royal Institute of Technology within the EU-IST project PCIC. It is demonstrated that Ar/Cl₂ CAIBE is a very promising method to obtain high aspect ratio etching of PCs in the InP-based materials. With this process, it is possible to obtain PC-holes as deep as 3 μm even for feature (PC-hole) sizes as small as 200-250 nm. The critical role of the sample temperature, hence the chemical etching component, in determining geometric parameters of the PC-holes such as depth, side-wall profile (size and shape) is examined. It is shown that good quality PCs can be etched only when the chemical and physical components in the etch process are balanced. The role of the mask material and the dependence of etch-depth on feature size are discussed. Optical properties of the etched PCs are used to evaluate the quality of the etched PCs and thereby identify the most promising dry etching processes and process conditions. Finally, limitations of reactive ion etching using hydrocarbon-based chemistry for PC fabrication in the InP system will be highlighted.